Lamp base



FIG. 1 is a front elevational view of a lamp base showing my new design;

FIG. 2 is a left side elevational view thereof; and

FIG. 3 is a perspective view thereof on an enlarged scale.

The lamp shade, harp, light bulb and light socket of FIGS. 1 and 2, and the harp, light bulb and light socket of FIG. 3 shown in dotted outline form are environmental structure and are not part of my design sought to be patented. 

The ornamental design for a lamp base, as shown and described. 